Field
Embodiments of inventive concepts relate to a touch analog front-end (AFE), and more particularly, to a touch AFE that improves operation of a touch input device.
Description of Related Art
A user may input information such as a numbers into an electronic device such as a cellular phone, tablet, or computer, for example, using a keypad device such as a touch screen. Because a keypad's visibility may be reduced (in low light situations, for example), the accuracy of the keypad input device is of significant importance.
Touch screens are typically either pressure sensitive or capacitive. Pressure sensitive screens employ pressure-sensitive devices that alter resistance in response to pressure and capacitive screens employ a capacitor to sense the amount of discharge from a charged surface of a screen when touching the surface of the screen. Currently, the capacitive type which has high-resolution and good sensitivity has been widely used.
A hover touch recognition function which extracts information about a position (i.e., a coordinate) and a height of a finger floated over a screen of a mobile device has been applied to a commercial appliance. A technique such as the hover touch requires high level sensitivity and the performance of the hover touch may be seriously degraded due to external noises. Such noise sources may include display noise, power line noise, burst noise, and charger noise, for example.